Windows Nightly Rust builds failing

[SWilson4]

The Windows Nightly Rust builds are failing. I do not have the expertise on Windows or Rust to debug this, so I propose disabling them to allow the rest of the CI tests to pass.

I don't believe that this is due to any change in liboqs or liboqs-rust, so hopefully it will resolve itself. I will periodically try re-enabling the builds to see if this happens.